Conversion of hydrocarbon oils



Aug. 16, 1938. R. PYZEL coNvERsIoN oF HYDRocARBoN oILs ,f Y NZON ZOFwDmEOU Original Filved Dec. l2, 1952 ESOP lNVENTOR ROBERT PYZEL Patented Aug. 16, 1938- 4 IPATENT OFFICE v2,127,009 y coNvElzsIoN or nrDRocAnBoN oILs Robert Pyzel, Chicago, Ill., assignor to Universal Oil Products Company, Chicago, Ill., a corporation of Delaware Application December 12. 1932, .Serial No. 646,794

Renewed January 14, 1937,

s claims. (cilA 19e-e1) The present invention is directed to improvements in the type of cracking process and apparatus wherein. hydrocarbon oil vapors are brought into direct contact and commingle with hot combustion gases to effect conversion of the oil iorthe production of high yields of lower boiling hydrocarbons such as motor'fuel of high antif knock value.

In processes of the type mentioned, the comlo bustion gases, which .serve as a heat carrying medium for the main cracking reaction by direct contact and commingling with the oil to be treated, are preferably substantially devoidof excess air or free oxygen in order to avoid combustion l5 or excessiveoxidation of the hydrocarbon oil undergoing treatment. However,v high combus-v tion temperatures result from burning any ordinary type of fuel without great excess air and when fresh combustion products generated un- 20 der such conditions are brought into direct contact with hydrocarbon oil, the reaction will result in the formation of major yields of gas and an excessive quantity of coke with a minor production of liquid products. It is the purpose of 25 the present invention to reduce and control the temperature of the heat-carrying medium by introducing controlled quantities oi' water into the fresh hot combustion products, prior to their admixture with the hydrocarbon oil vapors-to be treated. This results' in the generation of superheated steam from the 4water thus-introduced, which serves to dilute and cool the combustion gases to the desired temperature. There are additionaiadvantages in the introduction of` water into the heating medium, e. g., it has'bee'n found to exert a beneficial action upon the operation and the oil undergoing conversion, as well as upon the conversion products, especially the overhead distillate, rendering rening of the same 40 much easier and resulting in the productionof a sweeter and more stable light distillate product of better color, as compared with the'product from. the same type of process not utilizing water and/or steam. Furthermore, less carbon and pitchy matter appears to be produced under these conditions and-the overhead Aproduct of the process is richer in hydrocarbons and higher in B. t. u. value and recovery of gasoline theref'rom is rendered easier and more, economical. I Water has been found more suitable as a diluent and cooling medium for the -fresh combustion products than non-condensable gases, such as relatively cool spent combustion gases or a mixture of the same with the gaseous products ot the process which have previously been used in cracking processes of the general character described, as a smaller volume of cooling medium is necessary for a given reduction in temperature when, Water is employed due, in part, yto the latent heat of 'vapcrization required for conversion of 5 the water into steam. This reduces the volume of vapors Ihandled for a givenchar'ging capacity,

- from the gaseous products of the process is particularly beneficially 'affected whenwater is utilized as the cooling medium for the combustion 15 gases as the steam generated may be condensed to Water and separated from the gases, prior to the scrubbing stage, whereas when relatively cool spent combustionproducts are employed as the cooling medium, the total volume of iixed gases 20 is greatly increased; Also the cost, character and capacity of the equipment required for injecting Water, -as well as theoperating costs of such equipment, are very much less than those required for compressing and injecting gaseous 25 cooling media 'into the system.

e The accompanying diagrammatic drawing illustrates one specific form of apparatus embodying the features of the present invention and wherein the process of the invention may be practiced. 30

However, it is not intended to limit the invention througlrdine 4 andvalve 5 to heating coil 6.

When desired, a portion or all of the raw oil charging stock, instead of passing directly to heating coil 6, may be diverted from line 4 through line 1 and valve 8 into the residuum 40 separating column 9, wherein it is preheated by direct contact with the hot ascending cracked vapors, vserving to assistin cooling the vapors sufficiently -to condense and separate therefrom the heavy ends which form the residual liquid conver- 45 sion product ofthe process. All or a major portion of the raw loil maybe lvaporized by contact with the hot conversion products in column 9 but, by introducing the raw oil into column 9,

a means is aii'orded'of separating therefrom any 50 heavy ends which itis not desired vto subject to the relatively severe conversion conditions in the' mixing and conversion, stages of the process, while the lower boiling portions of the raw oil,

desirable as cracking stock for the major crack- 55 ing operation of the process, are vaporized in column 9, passing therefrom through line I0 and valve II to condensation in the fractionator or reflux separating column I2, to be withdrawn therefrom, together with the insuiiiciently converted components of the cracked vapors condensed in this column as reux condensate, through line I3 and valve I4 to pump I5 by means of which the oil is directed through line I6, valve I1 and line 4 to heating coil 6.

Heating coil 6 is located in the furnace I8 of any suitable form capable of furnishing the heat required to bring the oil to the desired temperature under the desired pressure conditions. In all cases the oil is heated in heating coil 6 to a temperature sufficient to insure substantial subsequent vaporization and usually a relatively mild conversion temperature of the order of 850 to 950 F. is employed at the outlet from the heating coil, although any conversion which may take place in this zone is incidental to the main cracking reaction subsequently accomplished by contact between the hydrocarbon vapors and the heat carrying medium from the combustion zone. Any desired pressure ranging from substantially atmospheric to a superatmospheric pressure of several hundred pounds per square inch may be employed in the heating coil and the heated oil is discharged therefrom through line I9 and valve 20 into' the mixing and reaction chamber 2|.

Simultaneous with the operation above described, fresh combustion gases are generated in combustion zone 29. Any suitable fuel such asoil, gas or pulverized solid fuel is supplied to a burner 24 of .any suitable form through line 22 and valve 23 while air, in an amount approximate to that theoretically required for complete combustion, is supplied through line 25 and valve 2B, care being exercised to introduce no substantial amount of excess air to the combustion zone for the reasons already given. Combustion zone 29, in the particular case illustrated, comprises a metal shell 30 with suitable refractory lining 3|, which is capable of withstanding super-atmospheric pressures up to pounds, or thereaboutsy per square inch so that combustion may, when desired, be accomplished at super-atmospheric pressure, permitting the use of a similar pressure in the mixing and reaction chamber 2l. Since unusually high flame-burst temperatures res-ult from the use of little or no excess air and super-atmospheric pressure, steam supplied through line 21 and valve 28'to burner 24 may be introduced to the combustion zone with the combustible fuel-air mixture in an amount suflicient to reduce the temperature in the combustion zone to below the fusion point of the refractorylining 3l. Water is introducedv through line 39 and valve 40 into direct contact with the hot combustion gases leaving combustion zone 29, serving to cool the combustion gases to the desired temperature, prior to their contact with the hydrocarbon oil vapors from heating coil 6. The resulting mixture of steam 4and combustion gases passes through duct 4I into the mixing and reaction chamber 2|, preferably entering this zone at a temperature of the order of 1400 to 2200i F. I have found that any desired temperature within this range may be obtained by the regulated introduction of water in an amount suflcient to generate 25 to 50 percent by volume of the total heat carrying medium, comprising combustion gases and steam. As a means of comparison it should be remembered that the amount of steam ordinarily formed as a product of combustion residuum separating column 9, wherein the heavy residual conversion products are condensed and separated from the -vaporous conversion products, raw oil being supplied, when desired, to this zone as already described, to serve as a medium for assisting cooling and condensation of the heavy conversion products. The residual liquid separated from the vaporous conversion products in column 9 maybe Withdrawn from its lower portion through line 48 and valve 49 to cooling coil 50 from which it is withdrawn through line 5I and valve 52 to pump 53, passing therefrom through line 54 from. which it may be directed, all or in part, to storage or to any desired further treatment through line 56 and valve 51. When desired, a portion of the cooled residual oil may be recirculated through valve 55, in line 54, to column 9 to serve as a cooling and reuxing medium. I

Vapors remaining uncondensed in column 9, including all of the vaporous conversion products supplied thereto, of lower boiling point than the residual liquid and, when raw oil is introduced into column 9, all of the raw oil with the exception of any heavy components boiling within the range of the residual conversion products, pass,

together with the combustion gases and steam,`

from the upper portion of column 9 through line I0 and valve II to fractionation in the fractionatingor reflux separating column I2, wherein the heavy components of the vapors supplied distillate product of the system, are condensed as reflux condensate to be returned, as already described, to heating coil 5 or residuum separating chamber 9.

The fractionated vapors, combination gases and steam pass from the upper portion of column I2 through line 58 and valve 59 to condenser 60. wherein steam and a large portion of the hydrocarbon distillate product of the process is condensed, passing, together with the process gases,

' through line 6I into condensing tower ,52, whereinfurther condensationto recover all but a minor portion o the desired light vdistillate product of the process is accomplished. The condensed hydrocarbon distillate and water passes from the lower portion of tower valv: S4 to separator 65, from the lower portion of which the water is withdrawn through line 32 while the distillate is withdrawn from the 62, through line 63 and to this zone, boiling above the range of the desired light4 sufiiciently low to condense sustantially all of the liquids available by condensation from the vaporous products of the process, is employed in column 62 and, as an example of one means of accomplishing the desired degree of cooling in tower 62, a portion of the distillate from receiver v 2,127,oo9 65, cooled to the riquired subatmospheric temdrawn from the upper portion of tower 62 through line 18 and valve 19 and may, when desired, be supplied to a suitable scrubber or absorber, not shown, of any well known form, for the recovery of additional light liquid products which may,` when desired, be blended with the distillate recovered from separator 65 to form the total light distillate product of the system.

Water separated from the distillate in receiver 65 and withdrawn therefrom through line 32, as already indicated, may be removed, all or in' part, from the system through line 34 and valve 35 but preferably the major portion of the water recovered passes through valve 33, in line `32, to pump 38, 'by means of which it is returned through line 39 and valve 40 to combustion zone 29. In this manner a continuous cycle of direct contact cooling medium is set up within the system, this system comprising one of the features of the invention. .The amount of water recovered in separator 65 will normally be in excess of that required for the .cycle inasmuch as it comprises the water condensed fromthe total steam 'in the `36 containing control valve 31. It is to be understood that water may beintroduced into the system from any outside source but that the water obtained from the receiver is preferred as it is distilled and isA free from scale forming materials and pumping costs are reduced since the pressure dierential may be less from the receiver to the system than from an outside source.

As already indicated, the temperature to which the hydrocarbon, oil to be treated is heated and vaporized, prior to its contact with the mixture of combustion gases and steam, is preferably within the range of 850 to 950 F. and this heating is'preferably accomplished at a substantial super-atmospheric pressure within the range of 100 to 500 pounds, or thereabouts, per square inch although, when desired, lower temperatures or pressures, or both, may be employed. The heat carrying medium preferably enters the mixing and reaction chamberat a temperature, as already stated, of from 1400 to 2200 F., or thereabouts, and in an amount suilicient to maintain the resulting mixture of combustion gases, steam and hydrocarbon oil vapors at a temperature within the range of 900 to 1100 F. in the mixing and reaction chamber. The conversion time afforded `the mixture .in the reaction chamber is preferably not less than one minute and not more than approximately three minutes and, although. not illustrated in the drawing, the neaction chamber is preferably well insulated to prevent the excessive loss of heat by radiation and maintain the mixture within or not appreciably below the temperature range given .during its time in this zone. Any desired pressure ranging from substantially atmospheric to a super-atmospheric pressure of 150 pounds, or thereabouts, per square inch may be maintained in the combustion zone and in the succeeding mixing and reaction chamber. The pressure employed in the' succeeding portions of the system may be substantially equalized with orsomewhat reduced relative to the pressure employed in the reaction chamber. v

As aspecic example of one operation of the process of the present invention, the charging stock is a 33 A. P. I. gravity gas oil which is supplied to the residuum separating chamber of the system, raw oil vaporized in the residuum separating chamber and subsequently condensed with the reflux condensate in the fractionator of the system is supplied, with the reflux condensate, in the proportion of about two parts of reflux to one part of raw oil condensate, to a heating oil wherein it is subjected to a relatively mild conversion temperature of approximately 900 F. atasuper-atmospheric pressure of about 300 pounds per square inch, at which temperature it is introduced into the mixing and reaction chamber, which is maintained at a superatmospheric pressure of about 100 pounds per squareinch. Simultaneously combustion gases are generated from vthe combustion of' fuel oil with no appreciable excess air -at a superatmospheric pressure of. about 100 pounds per square inch. Suiiicient steam is introduced into the combustion Zone with the fuel to cool the fresh combustion products and preventthe .rapid deterioration of the walls. of the combustion zone. Additional Water is introduced into the combustion gases, prior to their entrance into the mixing and reaction chamber, to bring the temperature of the resulting mixture to about 1500 F., about one part, by volume, of steam being required in the mixture to two parts cf combustion gases. 'I'he heat carrying medium is then commingled with the hydrocarbon oil vapors with a resulting temperaturevof about 980 F. for the mixture which is subjected to a conversion time of approximately two minutes in the. reaction chamber.

An operation such as above described may yield, per barrel of charging stock, about 64 percent of distillate` containing 'about 94 percent of 50 A.P. I. gravity motor fuel having an antiknock value equivalent to an octane number of approximately 84. The residual oil produced amounts to about '17 percent of the charging stock and is of exceptionally good quality with respect to suspended coke and B. S., as compared with residual oil from similar operations not utilizing water or steam as a cooling medium. The remaining 19 percent, or thereabouts, based on the charging per thousand cubic feet of process gases, still entrained in the gases after they have been subjected to scrubbing by ordinary means. Since the process of the present invention reduces by about one-third the volume of uncondensable gases in the heat carrying medium (about one-third of the heat carrying medium being steam) there is a corresponding reduction in the nal process gases and a corresponding reduction in the loss of desirable liquid products entrained therein.

I claim as my invention:

1. A process for the conversion of hydrocarbon oils which comprises heating an oil to a relatively mild conversion temperature in a heating coil and introducing it in vaporous form into a mixing and reaction chamber, simultaneously generating fresh combustion products and introducing thereto controlled quantities of Water, commingling the resulting mixture of combustion gases` and steam with the hydrocarbon oil vapors in the mixing and reaction chamber wherein the hydrocarbon oil vapors are subjected at their attained temperatureto a predetermined conversion time, withdrawing the resulting products from the reaction and mixing chamber and separating the residual material therefrom, subjecting the vaporous products to fractionation for the removal therefrom of insufllciently converted components which are condensed as reflux condensate, returning the reflux condensate to the heating coil for further treatment, subjecting the vaporous materials remaining uncondensed by fractionation to condensation, separating the resulting products into hydrocarbon oil distillate, water and gaseous products and commingling water con-V densate recovered from the operation with the freshly generated combustion gases, as heretofore described.

2. A process for the conversion of hydrocarbon oils which comprises heating` an oil to a conver'- sion temperature of 850 to 950 F. at a' superatmospheric pressure of from 100 to 500 pounds, per square inch in a heating coil and introducing it in vaporous form into a mixing and reaction chamber, simultaneously burning hydrocarbon fuel at super-atmospheric pressure, without appreciable excess air but with the controlled introduction of steam into the combustion zone with the fuel, introducing Water into the freshly generated combustion products in quantities sufficient to produce a temperature of the order of 1400 to 2200 F. in the resulting mixture of combustion gases and steam, commingling the mixture with the hydrocarbon oil vapors in the mixing and reaction chamber at a super-atmospheric presure of the'order of 50 to 150 pounds per square inch, subjecting the hydrocarbon oil va' pors admixed with the heat carrying medium to a conversion time of from one to three minutes in the reaction chamber, withdrawing the resulting conversion products and heat carrying medium from the reaction chamber, commingling therewith-raw oil charging stock for the process in a residuum separating zone and separating residual materials fromthe resulting mixture, subjecting vaporous materials from the residuum separating zone to fractionation, for the removal therefrom of insuiciently converted components which are condensed as reflux condensate, returning the reflux condensate to the heating coil for further treatment, subjecting the vaporous materials remaining uncondensed by fractionation to condensation, separating the resulting products into hydrocarbon oil distillate, water and gaseous products and commingling a portion of the water condensate recovered from the operation with the freshly generated combustion gases, as heretofore described.

3.` In the cracking of hydrocarbons by contact with hot combustion gases, the improvement which comprises generating the gases by burning fuel at a point of combustion out of contact with the hydrocarbons to be cracked, injecting water in liquid condition into the gases beyond the point of` combustion in an amount suiiicient to cool'the'gases to below 2200 F. but insufficient to cool the gases to below the cracking temperature of the hydrocarbons, and subsequently commingling the resultant mixture of combustion gases and steam with the hydrocarbons in suflicient quantity to crack the latter, condensing the cracked vapors and steam and separating the oil condensate from the water condensate, and utilizing suchwater condensate to cool the combustion gases as aforesaid.

ROBERT PYZEL. 

